Stratigraphy and interregional correlation of the Cenomanian-Turonian transition in the Western Interior of the United States near Pueblo, Colorado, a potential boundary stratotype for the base of the Turonian stage
Stratigraphy and interregional correlation of the Cenomanian-Turonian transition in the Western Interior of the United States near Pueblo, Colorado, a potential boundary stratotype for the base of the Turonian stage
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科罗拉多州普韦布洛附近美国西部内陆地区塞诺曼阶-土伦阶过渡的地层学和区域间对比，是土伦阶底部的潜在边界层型
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
W. A. Cobban
中科院分区：
文献类型：
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作者：
W. Kennedy;W. A. Cobban
位于科罗拉多普韦布洛的塞诺曼-土伦界线层序，以绿角石灰岩桥溪段的下部为代表。上Cenomanian菊石带，从最古老到最年轻的，Sciponoceras gracile和Neocardioceras juddii，而成功的Cenomanian scotti带的基地的位置推断与部分在东南部科罗拉多。以菊石术语表示的土仑期基底位于Watinoceras devonense带的基底，Watinoceras devonense带是西部内陆层序的一个新的生物地层单位;它之后是Pseudaspidoceras flexuosum、Vascoceras（Greenhornoceras）birchbyi和Mammites nodosoides带;随后的Collignoniceras woollgari带的基底标志着中土仑期的基底。四个inoceramid区被确认，Inoceramuspictus区横跨S。纤细到N. scotti区;糠虾的基部。sackensis带位于W.泥盆带; Mytiloides columbianus带的基部对应于Pseudaspidoceras flexuosum带的基部; Mytiloides mytiloides带的基部位于Mammites nodosoides带的基部上方一定距离处。在1984年哥本哈根白垩纪阶段界线讨论会上提出的9个可能的界线标志层位可以在这个序列中识别出来，这些层位与可进行绝对定年的辉长岩的存在一起，使普韦布洛序列成为一个强有力的候选者，可以考虑作为土伦阶的边界层型。普韦布洛序列与英格兰南部的序列相关联，在英格兰南部，从Metoicoceras geslinianum带的底部到Collignoniceras woollgari带的底部，也可以识别出科罗拉多的10个层位;这些层位在每个地区的相对位置相同。
The Cenomanian-Turonian boundary sequence at Pueblo, Colorado, is represented by the lower part of the Bridge Creek Member of the Greenhorn Limestone. Upper Cenomanian ammonite zones are, from oldest to youngest, those of Sciponoceras gracile and Neocardioceras juddii, while the position of the base of a succeeding Cenomanian Nigericeras scotti zone is inferred from correlation with sections in southeast Colorado. The base of the Turonian in ammonite terms is drawn at the base of the Watinoceras devonense zone, a new biostratigraphic unit for the Western Interior sequence; this is succeeded by zones of Pseudaspidoceras flexuosum, Vascoceras (Greenhornoceras) birchbyi and Mammites nodosoides; the base of the succeeding Collignoniceras woollgari zone marks the base of the middle Turonian. Four inoceramid zones are recognized; the Inoceramus pictus zone spans the S. gracile to N. scotti zones ; the base of the Mytiloides aff. sackensis zone is just below the base of the W. devonense zone; the base of the Mytiloides columbianus zone correponds to the base of the Pseudaspidoceras flexuosum zone; the base of the Mytiloides mytiloides zone lies some way above the base of the Mammites nodosoides zone. Nine horizons suggested as possible boundary markers at the 1 984 Copenhagen Symposium on Cretaceous Stage Boundaries can be recognized within this sequence which, together with the presence of bentonites that are amenable to absolute dating, makes the Pueblo sequence a strong candidate for consideration as a boundary stratotype of the Turonian Stage. The Pueblo succession is correlated with that in southern England, where ten horizons recognized in Colorado can also be recognized in the interval from the base of the M etoicoceras geslinianum zone to the base of the Collignoniceras woollgari zone; these are in the same relative position in each region.